Method and device for drilling a hole in ground or rock material and forming a brace

ABSTRACT

Disclosed are a method and a device for drilling, particularly percussion drilling or rotationally drilling, a hole ( 2 ) in ground or rock material and forming a brace in said hole ( 2 ). According to the invention, a borehole ( 2 ) is formed by a bit ( 7 ) that is mounted on drilling rods ( 1 ), and a brace is formed by at least one expanding element ( 12 ) that is mounted along the circumference of the drilling rods ( 1 ) and is brought, especially by expanding the same, into a position in which the expanding element ( 12 ) penetrates or rests against the material ( 22 ) surrounding the borehole ( 2 ), thus allowing for reliable bracing immediately after creating a borehole ( 2 ).

The present invention relates to a method for drilling, particularly percussion or rotary percussion drilling, a hole in ground or rock material and forming a brace or anchorage in said hole, wherein a borehole is formed by a drill bit mounted on a drill rod assembly, as well as to a device for drilling, particularly percussion or rotary percussion drilling, a hole in ground or rock material and for forming a brace or anchorage in said hole, wherein a drill bit for forming a borehole is mounted on a drill rod assembly.

In the context of the production of a hole or borehole in soil or rock material and the subsequent formation or fixation of an anchorage or lining in the borehole, it is, for instance, known from WO 98/21439 and WO 98/58132 to introduce an envelope tube into the borehole during the drilling procedure, for instance percussion or rotary percussion drilling, whereupon, after the completion of the bore, part of the drill bit is optionally removed from the borehole together with the drill rod assembly, while the envelope tube remains within the borehole such that an anchor will subsequently be formed within the borehole by filling a curing mass into the same. According to the configuration set out in WO 98/58132, the drill rod assembly may be provided with additional ribs and grooves on its outer circumference so as to ensure an accordingly good anchoring effect in case the drill rod assembly remains within the borehole, which is subsequently filled.

Alternatively, it is known to remove the drilling tool together with the drill rod assembly from a borehole after the production of the borehole, whereupon an anchor or anchoring device is subsequently introduced into the borehole, it being, for instance, referred to U.S. Pat. No. 4,305,687 A, U.S. Pat. No. 4,380,407 A, CH 476129 A, WO 94/05900 A, DE 916286 C, U.S. Pat. No. 4,516,883 A, EP 0354760 A, AT 339239 B and WO 2005/040556 A. In that known prior art, expandable anchoring elements are introduced into the borehole after the production of the borehole and subsequent removal of the drilling device, which expandable anchoring elements, during the introduction into the borehole, are maintained at a diameter reduced relative to the borehole, whereupon expandable subsections of the anchoring device, which are folded during their introduction or generally reduced in terms of cross section, are expanded after the complete introduction into the borehole. That known prior art involves the drawback that the borehole has to be made in a first method step, whereupon, after the removal of the drilling tool plus drill rod assembly, the anchoring device is introduced into the optionally very long borehole in a further method step, whereupon abutment on the borehole wall is to be subsequently accomplished by widening the outer diameter of the anchoring device. It is immediately apparent that not only an accordingly increased amount of time will be required for the two separate operating steps, but that an optionally subsequent introduction of such an anchoring device of great length will entail difficulties. Furthermore, it is to be anticipated that the removal of the drilling device together with the drill rod assembly and the subsequent introduction of an anchoring device is feasible only in comparatively solid soil or rock, wherein it must be safeguarded that no material will, for instance, break into the borehole during the drilling procedure or after the removal of the drilling tool and prior to the final introduction of the anchoring device, which material would block the borehole so as to render the introduction of the anchoring device impossible.

In addition, it is, for instance, known to arrange so-called packers on the outer circumference of a drill rod assembly of a drilling device, which, after the completion of the bore, enable an expansion into abutment on the borehole wall over a short subsection, thus counteracting a retraction or removal of the drill rod assembly from the borehole. A reliable anchoring effect, in particular when providing a plurality of anchors to be adjacently arranged, in order to ensure the stabilization of surrounding soil or rock material will, however, not be achieved by such packers, thus calling for additional anchoring means, if required, such as, for instance, the application of a curable material.

The present invention aims to avoid the problems of the above-mentioned prior art and to provide a method and a device of the initially defined kind, which enable a reliable anchorage at a reduced time expenditure and simple construction immediately after the completion of a borehole, wherein the removal of a drilling device and the separate and subsequent introduction of an anchoring device are, in particular, to be avoided.

To solve these objects, a method of the initially defined kind is essentially characterized in that after the completion of the borehole, an anchorage is formed by at least one expanding or spreading element mounted along the circumference of the drill rod assembly, which spreading element is brought, particularly expanded, into a position penetrating into, or resting against, the material surrounding the borehole. Since, upon completion of the borehole, an anchorage is formed by at least one spreading element mounted along the circumference of the drill rod assembly, it will be safeguarded that any additional and time-consuming method steps for removing the drilling device from the produced or completed borehole and subsequently introducing and anchoring or bracing a separate anchoring device, which have been required when providing a separate anchorage according to the prior art, will be obviated so as to enable a direct and reliable anchorage even in possibly loose material surrounding the borehole, without having to fear, for instance, the at least partial intrusion of material into the borehole during the removal of the drilling device and the subsequent introduction of the anchoring device. In this respect, it is provided that the at least one spreading element is, in particular, expanded into a position penetrating the material surrounding the borehole such that no obstruction or impairment by the at least one expandable spreading element need to be feared during the drilling procedure, while the at least one spreading element is placeable and, in particular, expandable into abutment on the surrounding material, or into a penetrating position in accordingly loose surrounding material, after the completion of the borehole. Such an expandable spreading element can be arranged relatively close to the drill bit in order to achieve an accordingly safe anchoring effect immediately behind the drill bit.

In order to achieve a reliable anchoring effect opposing, in particular, forces acting in the sense of retracting the anchoring device formed by the drilling device and, in particular, the drill rod assembly after having set the at least one spreading element, it is proposed according to a preferred embodiment that the at least one spreading element is expanded into a position oriented opposite to a drill-driving direction, into the material surrounding the borehole. Such an orientation opposite to the drill-driving direction, of the at least one spreading element will ensure that, under the action of forces in the sense of retracting the drilling and anchoring device from the borehole, the expandable spreading device will more deeply penetrate the surrounding material and achieve a more direct and firm abutment on the material delimiting the borehole, thus increasing or enhancing the anchoring effect to be achieved by the at least one spreading element.

For a particularly reliable expansion of the at least one spreading element after the completion of the bore or termination of the drilling procedure, it is provided according to a further preferred embodiment that the at least one spreading element is brought into the expanded position by being acted upon by an element coupled with the drill rod assembly, at a rotational movement of the drill rod assembly contrary to a rotational movement for producing the borehole. It is thus feasible in a simple manner, merely by reversing the direction of rotation of the drill rod assembly subsequently forming the anchor or anchoring rod, to bring the at least one expandable spreading element into abutment on the material delimiting the borehole, or into a position penetrating the surrounding material.

To support the expansion movement of the at least one spreading element, it is provided that the at least one spreading element is expanded by a relative movement along the longitudinal axis of the drill rod assembly relative to a stop element which is mounted on the drill rod assembly so as to be immovable in the axial direction, as in correspondence with a further preferred embodiment of the process according to the invention.

If a further drilling procedure is to be reliably prevented, and/or the chance of a possibly unintentional detachment of the anchorage is to be likewise prevented where necessary, it is proposed according to a preferred embodiment that, after the expansion of the at least one spreading element, at least a rotational movement in the direction of the rotational movement for producing the borehole is prevented. It will thereby be safeguarded that a provided mounting of the at least one spreading element will be safely maintained.

To solve the above-mentioned objects, a device of the initially defined kind is, moreover, essentially characterized in that at least one expanding or spreading element is mounted on the outer circumference of the drill rod assembly and, after the completion of the borehole, is capable of being brought, particularly expanded, into a position penetrating into, or resting against, the material surrounding the borehole, a stop coupled with the drill rod assembly so as to be immovable in the axial direction at least during the expansion movement of the at least one spreading element is provided at a distance from the position of the at least one spreading element on the outer circumference of the drill rod assembly, via which stop the at least one spreading element is expandable. As already pointed out above, it is thereby feasible in a simple manner without necessitating the removal of the drilling device and the subsequent introduction of an anchoring device immediately after the completion of the borehole or termination of the drilling procedure, to achieve a safe and reliable anchoring effect.

According to a preferred embodiment it is provided that the at least one spreading element is expandable into a position penetrating the material surrounding the borehole contrary to the drill-driving direction after the completion of the borehole. As already pointed out above, it is thereby, in particular, feasible to provide an increasing anchoring effect relative to forces acting in the direction or sense of retracting the anchor from the borehole. Such an orientation of the at least one expandable spreading element contrary to the drill-driving direction, in the event that a merely provisional anchorage is to be achieved, whereupon the drilling procedure is to be continued and the borehole is to be driven further, will, moreover, safeguard that the at least one expandable spreading element, at a new reversal of the direction of rotation of the drill rod assembly in the sense of continuing the drilling procedure, will again be removed from the position penetrating the surrounding material, or abutting position, so as to enable the continuation of the drilling procedure without obstruction by the at least one spreading element while increasing the depth of the borehole.

For a particularly simple and reliable expansion of the at least one spreading element, it is provided according to a preferred embodiment that the at least one spreading element is expandable into the position penetrating the material surrounding the borehole by a rotational movement of the drill rod assembly contrary to a rotational movement for the production of the borehole. In this context, it is proposed, for a structurally particularly simple and reliable configuration, that the at least one spreading element, at a rotational movement of the drill rod assembly contrary to the drilling direction, is expandable into the position penetrating the material surrounding the borehole via a thread formed on a sleeve-like element cooperating with the drill rod assembly, as in correspondence with a further preferred embodiment of the device according to the invention.

For the reliable introduction of the at least one expandable spreading element and for the achievement of an appropriate anchoring effect, it is, moreover, preferably provided that the at least one spreading element, departing from a position substantially abutting the outer circumference of the drill rod assembly during the drilling procedure, is at least partially elastically deformed during the movement penetrating into the material surrounding the borehole.

To support the expansion movement of the at least one spreading element, it is provided according to the invention that a stop coupled with the drill rod assembly so as to be immovable in the axial direction at least during the expansion movement of the at least one spreading element is provided at a distance from the position of the at least one spreading element on the outer circumference of the drill rod assembly, via which stop the at least one spreading element is expandable, as in correspondence with a further preferred embodiment of the device according to the invention.

In order to provide an accordingly uniform expansion movement so as to achieve the reliable penetration of the at least one spreading element by the action of low forces even in rough environments, it is, moreover, preferably proposed that the at least one expandable spreading element, on its end facing the stop element, is configured with a ramp or profiling, which cooperates with an, in particular, complementary ramp or profiling provided on the stop element.

For the uniform distribution of an anchoring effect about the circumference of the drill rod assembly, it is, moreover, preferably proposed according to the invention that a plurality of expandable spreading elements are arranged in a manner substantially uniformly distributed about the circumference of the drill rod assembly.

In order to optionally achieve a reliable anchoring effect and distribution of forces to be introduced into the surrounding material via an anchor of greater length, which is formed by the drill rod assembly, it is, moreover, proposed that a plurality of expandable spreading elements are provided about the circumference of the drill rod assembly at different distances from the drill bit, as in correspondence with a further preferred embodiment of the device according to the invention.

In order to avoid any interference with, or impairment of, the drilling procedure and to secure the position of the spreading element during the drilling procedure, it is, moreover, preferably provided that the at least one spreading element is secured in its position substantially abutting the drill rod assembly by an additional retaining element during the drilling procedure.

In order to introduce the displacement forces required for expanding the spreading element upon termination of the drilling procedure as well as, in addition, to reliably introduce the forces required for percussion or rotary percussion drilling, it is further proposed that a bush mounted on the drill rod assembly and equipped with an external toothing is provided for transmitting the rotational movement from the drill rod assembly onto the drill bit, which bush, for the expansion of the at least one spreading element, is placeable into a position out of engagement with the toothing of the drill bit, or an element coupled with the drill bit, as in correspondence with a further preferred embodiment of the device according to the invention. Such a bush or toothed bush can be built in an accordingly massive and structurally simple manner as a function of the forces to be introduced both during the drilling procedure and during the expanding procedure.

To further support a desired expansion procedure of the at least one spreading element, it is, moreover, provided that the at least one spreading element, during the expansion procedure, is guided on the drill rod assembly and/or an element coupled with the drill bit by a linear guide extending substantially in the longitudinal direction of the borehole, as in correspondence with a further preferred embodiment of the device according to the invention.

As already mentioned above, it may be desired or possible to perform a drilling procedure after a temporary expansion of the spreading element by effecting a rotational movement of the drill rod assembly in the original direction of rotation for the production of the borehole. If such a further drilling procedure is to be reliably prevented while optionally also providing a reliable anchorage of the at least one spreading element without any chance of detachment of the latter, it is proposed according to a preferred embodiment that sleeve-like or bush-like elements mounted on the drill rod assembly are provided to at least prevent a rotational movement in the direction of the rotational movement for the production of the borehole, which sleeve-like or bush-like elements are formed with respectively complementary elevations or profilings on mutually facing end faces.

In the following, the invention will be explained in more detail by way of exemplary embodiments schematically illustrated in the attached drawing. Therein:

FIG. 1 illustrates a partial longitudinal section through a device according to the invention for carrying out the method of the invention during the drilling procedure, wherein at least one spreading element is substantially in abutment on the drill rod assembly;

FIG. 2 depicts the device according to the invention for carrying out the method of the invention in an illustration similar to that of FIG. 1, with the at least one spreading element being expanded into the material surrounding the borehole;

FIG. 3, in an illustration similar to that of FIG. 1, represents a partial longitudinal section through a modified embodiment of a device according to the invention for carrying out the method of the invention, wherein, in particular, locking against any further rotational movement is provided; and

FIG. 4 is an exploded view of individual elements of the embodiment according to FIG. 3 which are provided to achieve rotational locking and surround the drill rod assembly.

In the embodiment illustrated in FIGS. 1 and 2, a drill rod assembly is generally denoted by 1, which has a corrugated or thread-like shape, particularly on its outer surface, to serve as an anchoring rod after the completion of the borehole. During the drilling procedure indicated in FIG. 1, the transmission of a rotational movement of the anchoring rod or drill rod assembly 1, which is imparted by a driving means not illustrated and arranged outside the borehole 2, is effected via an end face 3 of a sleeve-shaped element 4 coupled with the drill rod assembly 1, which end face 3 cooperates with a bush or toothed bush 5 having an external toothing 6, which is coupled with an element or tappet 8 coupled with the drill bit 7 so as to transmit a rotational movement of the drill rod assembly 1 via the toothed bush 5 onto the tappet 8 and hence the drill bit 7, cutting or drilling elements being indicated by 9 and 10. The toothed bush 5 provided for transmitting the rotational movement is maintained in a position resting against the end face 3 by a spring 11.

During the drilling procedure, at least one subsequently expandable spreading element 12 is substantially in abutment on the outer contour of the drill rod assembly or anchoring rod 1 so as to prevent any interference with, or impairment of, the drilling procedure by the at least one expandable spreading element 12 during the drilling procedure.

A central axis of the drill rod assembly 1, and hence the entire drilling device, is denoted by 13.

After the completion of the borehole 2, the drill head or drill bit 7 is pressed at the interior of the borehole in the sense of the drill-driving direction or arrow 14, whereupon the drill rod assembly 1 is set into a rotational movement contrary to the driving direction for performing the drilling procedure.

By reversing the rotational movement, the end face 3 of the sleeve-like element 4 is moved out of engagement with an end face denoted by 15 in FIG. 2, of the toothed bush 5, which is displaced against the force of the spring 11 in such a manner as to cause the external toothing 6 of the toothed bush 5 to get out of engagement with a complementary toothing of the tappet 8 coupled with the drill bit 7 and no more rotational movement or torque to be transmitted from the drill rod assembly 1 to the drill bit 7.

The sleeve-like element 4 coupled with the drill rod assembly or anchoring rod 1 comprises a thread 16 on its outer surface, which, upon reversal of the direction of rotation of the drill rod assembly 1, causes the at least one expandable element or spreading element 12, which comprises a complementary thread 17, to be moved contrary to the drill-driving direction, which coincides with the application direction 14 of the drill head 7 in FIG. 2, along the outer surface of the drill rod assembly 1 as indicated by arrow 18. For a substantially linear movement of the at least one expandable element 12, a linear guide 19, 20 is, moreover, provided on the outer surface of the spreading element 12 and also in the subsection 21 of the tappet 8, which covers the spreading element 12, particularly during the drilling procedure.

For a selective expansion movement of the spreading element 12 into the material 22 surrounding the borehole wall 2, a stop 23 is additionally provided on the outer circumference of the drill rod assembly or anchoring rod 1 at a distance from the mounting of the spreading element 12. For a reliable guidance of the expansion movement, which can be achieved by the spreading element 12 penetrating the surrounding material 22, it is, moreover, provided that the spreading element 12 comprises a ramp or profiling 24 which cooperates with a substantially complementary ramp or profiling 25 of the stop element 23 in such a manner as to effect the expansion and penetration of the spreading element 12 and, in particular, its tip 26 into the surrounding material 22 by the linear movement of the spreading element along arrow 18, which is caused by the rotational movement via the mutually cooperating threads 16 and 17.

As indicated, the stop 23 is, moreover, coupled with a locking sleeve 27.

In order to prevent the at least one spreading element 12 from breaking during the expansion movement, or in the expanded position, as illustrated in FIG. 2, an elastically deformable region 28 of the spreading element 12 is additionally provided.

Due to the fact that the at least one expandable spreading element 12 penetrates into, or comes into abutment on, the surrounding material 22 against the drill-driving direction indicated by arrow 14, it will be ensured that the at least one expandable spreading element 12 will penetrate more deeply into the surrounding material 22, or come more firmly into abutment on the borehole wall 2, by the action of forces in the sense of arrow 18 indicating an extraction direction of the drill rod assembly or anchoring rod 1, thus providing elevated forces opposing any extraction.

In addition, the orientation of the at least one spreading element 12 opposite to the drill-driving direction 14 ensures that the present configuration may, for instance, also be used to achieve a provisional securement or anchorage, since a new reversal of the direction of rotation of the drill rod assembly or anchoring rod 1 in the sense of the drill-driving direction via the toothed bush 5 will cause recoupling of the drill rod assembly 1 with the drill bit 7 or the tappet 8, respectively, so as to enable the drilling procedure to be continued while the spreading element 12, due to the orientation of the mutually cooperating threads 16 and 17 is, at the same time, retracted into the position illustrated in FIG. 1 so as not to interfere with, or impair, a further drilling procedure.

For the uniform distribution of anchoring forces to be absorbed, a plurality of spreading elements 12 may be arranged or provided substantially uniformly about the circumference of the drill rod assembly 1.

In order to provide for securement in a position substantially abutting the drill rod assembly 1 during the drilling procedure, a securing ring 29 is, moreover, indicated in FIG. 1, which, during the drilling procedure, will, for instance, hold a plurality of uniformly peripherally distributed spreading elements 12 substantially in abutment on the drill rod assembly 1.

For the distribution of anchoring forces to be absorbed, along a drilling device 1 optionally having a greater length, it may, moreover, be provided that a plurality of spreading elements 12 are arranged or provided at different axial distances from the drill bit 7 and, in a favorable manner, substantially uniformly about the circumference of the drill rod assembly 1.

In addition, it may be provided that an envelope tube not illustrated in the drawings is, for instance, arranged immediately consecutive to the tappet coupled with the drill bit 7, or the element 8, so as to enable the at least one spreading element 12 and, in a favorable manner, a plurality of spreading elements 12 to emerge into the position illustrated in FIG. 2 through appropriate passage openings or slots in order to achieve an appropriate anchoring effect.

It has thus become possible to expand the at least one spreading element 12 into an anchoring or securing position as illustrated in FIG. 2 immediately upon completion of the borehole 2 by simply reversing the direction of movement or rotation of the drill rod assembly or anchoring rod 1.

In the embodiment according to FIGS. 3 and 4, the reference numerals of the preceding embodiments have been retained where possible. Also this configuration comprises an anchoring rod formed by a drill rod assembly 1, which, as will be discussed below, is provided with an external thread not illustrated, said anchoring rod or drill rod assembly 1 powering a drill bit again denoted by 7 in order to produce the borehole 2.

In the embodiment illustrated in FIGS. 3 and 4, a bush 30 similar to bush 5 is provided for transmitting the rotational movement of the drill rod assembly or anchoring rod 1 to the drill bit 7 as in the embodiment according to FIGS. 1 and 2, said bush 30 cooperating with a bush 31 comparable to element 4 in order to transmit a rotational movement onto a tappet 32, which will subsequently impart a rotational movement to the drill bit 7. In addition, a further sleeve-like or bush-like element 33 cooperating with the drill bit 7 is provided in the embodiment illustrated in FIGS. 3 and 4, wherein both the drill bit 7 and the sleeve-like element 33 comprise elevations or profilings 34 and 35, respectively, which will slide one above the other in the manner of a ratchet during the drilling procedure, thus enabling a rotational movement or drill-driving movement while effecting locking of the drill bit 7 during a rotational movement of the anchoring rod or drill rod assembly 1 contrary to the drilling device by the additionally provided application via a spring 36.

In order to achieve an appropriate locking effect, also the bushes or sleeves 30 and 31 in a similar manner are each provided with respectively complementary elevations or profilings 37 and 38, respectively, which will likewise cause locking at a reversal of the rotational movement.

Furthermore, an additional sleeve-like element 39 coupled with the element 32 is provided, which is coupled via a further sleeve-like element or socket 40 arranged within the same, wherein both the element 39 and the element 40 cooperate with the spreading element denoted by 41 during a reversing movement. It is, in particular, apparent from the illustration according to FIG. 4 that the socket-like or sleeve-like spreading element 41 is formed with a plurality of longitudinally extending slots 42 which, upon actuation of the drill rod assembly 1 contrary to the rotational movement for producing the borehole, cooperate with one another via complementary ramps 43 and 44, respectively, of the spreading element 41 and of a stop element 45 so as to enable the expansion of the individual spreading elements 41′ into an expanded position contrary to the drill-driving direction.

In order to reliably avoid an optionally desired further rotational movement after the expansion of the spreading elements 41′, also the sleeve-like or bush-like elements 39, 40 and the spreading element formed by a socket-like or sleeve-like element 41 are likewise each formed with complementary elevations or profilings 46, 47 and 48 in a manner similar to the sleeve-like elements 30, 31, 33 as well as the drill bit 7, in order to effect rotational locking as a function of the orientation to be provided. In this respect, it is to be anticipated that the element 40 will directly screw on a right-hand thread on the anchoring rod or drilling thread 1 and directly move on the anchoring rod or drill rod assembly 1 for expanding the spreading element or the individual subsections 41′, and the spreading element 41 will move over the stop element 45, thus causing the expansion of the spreading elements 41′ by a relative movement of the ramps 43 and 44.

In addition, the element 40 is mounted within the element 39 in a longitudinally displaceable, yet rotationally fast manner such that, taking into account the profilings or elevations or end toothings 46, 47 and 48, the respective end toothings or profilings 47 and 48 will cause rotational locking of the individual elements in the event that element 40 emerges from element 39 during the expansion movement of the spreading elements 41′, such that locking of the reached position of the spreading elements 41′ will be achievable by the provision of the respective end toothings or profilings.

If locking of the spreading elements 41′ is optionally renounced, the respective profilings will be obviated. 

1-14. (canceled)
 15. A method for drilling, particularly percussion or rotary percussion drilling, a hole in ground or rock material and forming a brace or anchorage in said hole, wherein a borehole is formed by a drill bit mounted on a drill rod assembly, wherein, after the completion of the borehole, an anchorage is formed by at least one expanding or spreading element mounted along the circumference of the drill rod assembly, which spreading element is brought, particularly expanded, into a position penetrating into, or resting against, the material surrounding the borehole, the at least one spreading element being expanded into the material surrounding the borehole into a position oriented contrary to a drill-driving direction, wherein that at least one spreading element, by relative movement along the longitudinal axis of the drill rod assembly, is expanded relative to a stop element mounted on the drill rod assembly so as to be immovable in the axial direction.
 16. The method according to claim 15 wherein the at least one spreading element is brought into the expanded position by being acted upon by an element coupled with the drill rod assembly at a rotational movement of the drill rod assembly contrary to a rotational movement for producing the borehole.
 17. The method according to claim 15 wherein after the expansion of the at least one spreading element, at least a rotational movement in the direction of the rotational movement for producing the borehole is prevented.
 18. A device for drilling, particularly percussion or rotary percussion drilling, a hole in ground or rock material and forming a brace or anchorage in said hole, wherein a drill bit for forming a borehole is mounted on a drill rod assembly, wherein at least one expanding or spreading element is mounted on the outer circumference of the drill rod assembly and, after the completion of the borehole, is capable of being brought, particularly expanded, into a position penetrating into, or resting against, the material surrounding the borehole, the at least one spreading element being expandable into a position penetrating the material surrounding the borehole contrary to a drill-driving direction after the completion of the borehole, wherein a stop coupled with the drill rod assembly so as to be immovable in the axial direction at least during the expansion movement of the at least one spreading element is provided at a distance from the position of the at least one spreading element on the outer circumference of the drill rod assembly, via which stop the at least one spreading element is expandable.
 19. The device according to claim 18 wherein the at least one spreading element is expandable into the position penetrating the material surrounding the borehole by a rotational movement of the drill rod assembly contrary to a rotational movement for the production of the borehole.
 20. The device according to claim 18 wherein the at least one spreading element, at a rotational movement of the drill rod assembly contrary to the drilling direction, is expandable into the position penetrating the material surrounding the borehole via a thread formed on a sleeve-like element cooperating with the drill rod assembly.
 21. The device according to claim 18 wherein the at least one spreading element, departing from a position substantially abutting the outer circumference of the drill rod assembly during the drilling procedure, is at least partially elastically deformed during the movement penetrating into the material surrounding the borehole.
 22. The device according to claim 18 wherein the at least one expandable spreading element, on its end facing the stop element, is configured with a ramp or profiling, which cooperates with an, in particular, complementary ramp or profiling provided on the stop element.
 23. The device according to claims 18 wherein a plurality of expandable spreading elements are arranged in a manner substantially uniformly distributed about the circumference of the drill rod assembly.
 24. The device according to claim 18 wherein a plurality of expandable spreading elements are provided about the circumference of the drill rod assembly at different distances from the drill bit.
 25. The device according to claim 18 wherein the at least one spreading element is secured in its position substantially abutting the drill rod assembly by an additional retaining element during the drilling procedure.
 26. The device according to claim 18 wherein a bush mounted on the drill rod assembly and equipped with an external toothing is provided for transmitting the rotational movement from the drill rod assembly onto the drill bit, which bush, for the expansion of the at least one spreading element, is placeable into a position out of engagement with the toothing of the drill bit, or an element coupled with the drill bit.
 27. The device according to claim 18 wherein the at least one spreading element, during the expansion procedure, is guided on the drill rod assembly and/or an element coupled with the drill bit by a linear guide extending substantially in the longitudinal direction of the borehole.
 28. The device according to claim 18 wherein sleeve-like or bush-like elements mounted on the drill rod assembly are provided to at least prevent a rotational movement in the direction of the rotational movement for the production of the borehole, which sleeve-like or bush-like elements are formed with respectively complementary elevations or profilings on mutually facing end faces. 